package com.hmdp.utils;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.hmdp.entity.Shop;
import lombok.AllArgsConstructor;
import lombok.NoArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import java.time.LocalDateTime;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;

import static com.hmdp.utils.RedisConstants.CACHE_NULL_TTL;
import static com.hmdp.utils.RedisConstants.LOCK_SHOP_KEY;

@Component
@Slf4j
public class CacheClient {
    private final StringRedisTemplate stringRedisTemplate;
    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);

    public CacheClient(StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
    }

    public void set(String key, Object value, Long time, TimeUnit unit) {
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(value), time, unit);
    }
    public void setLogicalExpire(String key, Object value, Long time, TimeUnit unit) {
        RedisData redisData = new RedisData();
        redisData.setData(value);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(unit.toSeconds(time)));
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(redisData));
    }
    public <R,ID> R queryWithPassThrough(String keyPrefix, ID id, Class<R> type, Function<ID,R> dbFallback,Long time, TimeUnit unit) {

        //解决缓存穿透
        String key = keyPrefix + id;
        String json= stringRedisTemplate.opsForValue().get(key);
        if(StrUtil.isNotBlank(json)) {
            return JSONUtil.toBean(json, type);
        }
        if(json!=null) {
            return null;
        }
        R r=dbFallback.apply(id);
        if(r==null){
            stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL,TimeUnit.MINUTES);
            return null;
        };
        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(r),time,unit);
        return r;
    }
    //利用逻辑过期解决缓存击穿
    public <R,ID> R queryWithLogicalExpire(String keyPrefix, ID id, Class<R> type, Function<ID,R> dbFallback,Long time, TimeUnit unit) {
        String key = keyPrefix + id;
        String json= stringRedisTemplate.opsForValue().get(key);
        if(StrUtil.isBlank(json)) {
            return null;
        }
        RedisData redisData = JSONUtil.toBean(json, RedisData.class);
        R r=JSONUtil.toBean((JSONObject)redisData.getData(), type);
        LocalDateTime expireTime = redisData.getExpireTime();
        if(expireTime.isAfter(LocalDateTime.now())) {
            return r;
        }
        String lockKey = LOCK_SHOP_KEY + id;
        boolean isLock=tryLock(lockKey);
        if(isLock) {
            CACHE_REBUILD_EXECUTOR.submit(()->{
                try {
                    R r1=dbFallback.apply(id);
                    this.setLogicalExpire(key, r1, time, unit);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }finally {
                    unlock(lockKey);
                }
            });

        }
        return r;
    }
    //利用互斥锁解决缓存击穿
    public<R,ID> R queryWithMutex(String keyPrefix, ID id, Class<R> type, Function<ID, R> dbFallback, Long time, TimeUnit unit){
        String key = keyPrefix + id;
        String json= stringRedisTemplate.opsForValue().get(key);
        if(StrUtil.isNotBlank(json)) {
            return JSONUtil.toBean(json, type);
        }
        if(json!=null) {
            return null;
        }
        String lockKey = LOCK_SHOP_KEY + id;
        R r=null;
        try {
            boolean isLock=tryLock(lockKey);
            if(!isLock) {
                Thread.sleep(50);
                return queryWithMutex(keyPrefix, id, type, dbFallback, time, unit);
            }

            if(r==null) {
                stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL,TimeUnit.MINUTES);
                return null;
            }
            this.set(key, r, time, unit);

        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }finally {
            unlock(lockKey);
        }
        return r;
    }
    private boolean tryLock(String key) {
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }

    private void unlock(String key) {
        stringRedisTemplate.delete(key);
    }

}
